Lecture 2 Part I Extemporaneous Compounding Flashcards
What is the purpose of extemporaneous compounding?
Allows the compounding pharmacist to work with the patient and the prescriber to customise a medication to meet the patients specific needs.
What is extemporaneous compounding?
Medications which are “made from scratch”
Individual ingredients are mixed together in exact strength and dosage required by the patient
What is trituration?
Form of icing used when incorporating finely divided insoluble powders or liquids into a base
What is trituration performed on?
Glass slab or tile
How is liquid incorporated into a base via trituration?
Make a well in centre of base
Pour in small amounts of liquid at a time into the well
Mix in well
Avoid air pockets (these will splash)
Why should air pockets be avoided when combining liquid into a base?
Air pockets will splash causing ingredients to go everywhere resulting in loss of product
What is levigation?
Form of mixing used for incorporating insoluble course powders into a base
What is levigation also known as?
Wet grinding
How do you levigate?
Rub down the powder with either a molten base or a semi solid base
Apply shearing force with the flat blade of the spatula against the slab to avoid a gritty product (similar to suppositories)
What is the doubling up technique?
Technique used to mix powder to powder,
Powder to semisolid
Or semisolid to semisolid
Especially when one ahi burnt is much smaller than the other
What is the doubling up technique done on?
Mortar (powder to powder) or it can be done on a slab
How is the doubling up technique done?
Start with small amount of each,
mix thoroughly,
Then double the volume each time as you continue to add an equal amount to what has been mixed
How do you add solids and liquids to a semi solid base?
Place weighed semisolid on glass slab
Place all weighed solids in more and mix Or place on glass slab and mix
Use doubling up technique to incorporate solids into base using a spatula
When mixed, make a well in the centre, carefully put in small amounts of liquid and mix within the well or score to mix
Continue until all liquid is well mixed in
What is an emulsion?
A thermodynamically unstable system consisting of at least 2 immiscible liquid phases
One phase is dispersed as globules in the other liquid
These are stabilised by an emulsifying agent
What are the two types of phases in an emulsion?
Dispersed phase (globules) Continuous phase (other liquid)
Why is an emulsifying agent needed?
The two phases don’t mix together naturally, so we need an agent to make then stay together
What is a disadvantage of a drug in an emulsion form?
Storage may be difficult
What do oral emulsions use?
Acacia gum
What is the ratio of an emulsion for fixed oils?
4:2:1 (oil:water:gum)
What is the emulsion ratio for mineral oils? (Liquid paraffin is a mineral oil)
3:2:1 oil:water:gum
What is the ratio for volatile oils?
2:2:1
What is the dry gum method for a primary emulsion?
Drain oil into a clean dry flat bottom mortar
Disperse acacia over the oil and mix gently
Add water all at once and stir briskly in one direction until a clicking sound and white frothy primary emulsion forms
Gradually dilute the primary emulsion with vehicle and dissolved ingredients
Transfer to a pre calibrated bottle. Label and dispense
What is the wet gum method of making an emulsion?
Add water to acacia gum and quickly trituration to make a mucilage
Add oil in small mounts to mucilage
Trituration thoroughly after each addition until a thick primary emulsion is formed
Stabilise by mixing for several minutes then add other ingredients
What are some problems for compounding emulsions?
Phase inversion (if oil and water separate. Often caused by incorrect ratio)
Cross contamination of water/oil caused by equipment not dry e,g, for dry method
Mortar too small and curved, head of pestle too rounded gives insufficient shear. Bigger mortars are better
Excessive mixing at first stage with dry gum method and oil
Diluting primary emulsion too soon and too rapidly
Poor quality acacia
